1. Field of the Invention
The present invention relates to a backlight driving device for driving a backlight that illuminates a display panel and to a display incorporating this backlight driving device.
2. Description of the Related Art
A liquid crystal display (LCD) has the advantage over a CRT display that its enclosure can be made thin. Because of this advantage, LCDs are widely used as displays for information technology devices (such as computers) and as TV receivers. Such a liquid crystal display has a backlight as its light source. The backlight illuminates the LCD panel from the rear.
In a related-art LCD, the luminance value of an image displayed on the LCD is controlled by supplying a drive signal as shown below to the backlight such that the backlight illuminates the panel. That is, in the related-art LCD, a drive signal is created. The drive signal is pulse width-modulated in such a way that the duty cycle increases with increasing the luminance value of the video signal. A voltage corresponding to the created drive signal is applied to the backlight, thus controlling the luminance value of the displayed image (see, JP-A-2004-252127 (patent reference 1)).
In this related-art LCD, in cases where no voltage is applied to the backlight for longer than a given period of time and thus the LCD is under low-temperature conditions, there is the possibility that even if the drive voltage is applied, the backlight is not driven and the panel is not illuminated due to dead band characteristics. Therefore, the backlight is driven according to a drive signal composed of a pulsed signal that is pulse width-modulated, for example, within a range where the duty cycle is kept at an effective value.